Conventionally, a creel for supplying a special thread such as a carbon fiber to a loom includes a spindle unit which rotatably supports a bobbin around which the thread is wound. As described in, e.g., patent literature 1, this spindle unit includes a spindle part having a rotatably supported rotating shaft, and a brake part for braking the rotating shaft.
The rotating shaft of the spindle part rotatably supports the bobbin around which the thread is wound. When attaching the bobbin to the rotating shaft of the spindle part, a worker holds the bobbin in his or her hand and inserts a bobbin-attaching rotating shaft into the core of the bobbin. The weight of the bobbin around which the thread is wound is sometimes about 10 kg.
An example of a fixing structure for fixing the bobbin to the rotating shaft of the spindle part is a structure in which an O-ring is interposed between the bobbin and bobbin-attaching rotating shaft.
When the thread is pulled by the loom, the rotating shaft of the spindle part rotates together with the bobbin.
The brake part of the spindle unit is, e.g., a hysteresis brake, and gives tension to the thread pulled out from the bobbin by braking the rotating shaft of the spindle part.
A hysteresis brake disclosed in patent literature 1 has a rotating shaft on which a brake torque acts. The hysteresis brake is mounted on a frame such that the rotating shaft of the hysteresis brake is parallel to the rotating shaft of the bobbin-attaching spindle part. The rotating shafts of the hysteresis brake and spindle part are coupled with each other via a gear and interlocked. Accordingly, the hysteresis brake applies a predetermined brake torque to the rotating shaft of the spindle part to which the bobbin is attached, thereby giving tension to the thread pulled by the loom.
A general hysteresis brake includes an annular yoke with an excitation coil built-in, or a field core, and a cylindrical hysteresis member having a rotating shaft which rotates together around the same axis.
The field core includes an inner circumferential magnetic pole positioned on the inner circumferential side of the field core, and an outer circumferential magnetic pole positioned on the outer circumferential side of the field core. The inner circumferential magnetic pole and outer circumferential magnetic pole form an annular space in the field core.
The cylindrical hysteresis member is inserted into this annular space of the field core.